Wireless signaling system



Sept. 9, 1924. 1,508,151

E. F. W. ALEXANDERSON I WIRELESS SIGNALING SYSTEM Original Filed April 19. 1916 Inventor" Ernst. F W.f\|exande1-son.

' His ALLornes.

Patented Sept. 9, 1924 10 Aug. 28,

" UNITED sures PATENT o ERNST I. W. ALEXANDEBBOH, OI SOBENEO ELECTRIC COMPANY, A.

Original applic Divided and this appll To all whom it may concern.

Be it known that I, EnNs'r F.

armnnson, a

residing at Schenectady,

citizen of the r certaln new 0 and experimentally,

" are alwa Wireless my application filed April N 92,156, now Patent No.

7 a specification.

My present invention relates 1 08 FFICE.

TA-DY, NEW Yolk, ASSIGNOB '1'0 GENERAL OBATION 0! NEW YORK.

WIRELESS SIGNALING SYSTEM.

W. Annx- United States,

county of Schenechave invented Signaling Systems (division of 19, 1916, Serial 1,465,961, dated 1923), of which the following is to wireless s1gnaling systems, and more particularly to a system in which means is overcoming the efi'ect of static provided for disturbances in the receiving instruments.

c d1sturbances occur continu- Electrostati ously in the atmosphere,

sending out electromagnetic waves of varying frequency, 0 which will in be referred absorbed by among the va signal which lyzed this clusion that a basis of any device to as ye some which that is, which have the the description which strays. These waves are e recelvmg antenna and ollows riety of waves absorbed there are in resonance, same length as a is to be received and consegl llently act upon the recei ving devices in Having anafundamental rule must be the effect of static disturbances.

nation between a uency originating t e signal must be b wave of ased on in character between these the strays were like and amplitud to that stron there would be no wa quency addition criminating between one and longer the period is d the signaling waves can the greater is the ch tinguishing difference 1n the amplitude variations if in nothing and order that th crimination character for receiving devi against fore be designed so can be distinguished by used for decreasing the Any discrimithe same frefrom static and from some difl'erence two waves. If

the signals both in free variation, and in ger than the signals, y conceivable for disthe other. The

uring which the strays e device be efi'ective for dissufiiciently Ion ces which are compari g peri The Still strays, it should therethat th e wave trains their at present used #65361, dated August 2!, 1m Renewed July 12,18. Serial constructed so as to take advantage of this law to a certain extent by uslng a highly resonant receivin circuit on which the si a1 can be allow to act for' a considerab e number of successive alternations. The reason why these devices do not entirely discriminate against strays is the fact that the receiving antenna is set in oscillation by static shocks and stray waves of short uration and thus the time during which the disturbance can act upon the receiving device is prolonged to about the same degree as the signal.

One of t e objects of my invention is to provide a means for durin which the ative effect commercially are signal on the disturbances can act.

In attaining this object I make use of a tuned circuit of lower than radio but above audibility, for efiecting the p longation of the time during which the si nal and disturbance may be compared. The desired lower frequency is provided by means of interference beats between two radio frequencies. Both of these frequencies may be produced at the sending station, but in the resent application one of them is produced at the receiving station. An arrangement of this kind is more efiective t an one employing a single radio "frequency because it is more selective and roof against interference, both equencies ing necessary to produce an impression in the receiver. Also when means is provided at the sending station for establishing the beat frequency a less delicate adjustment of frequency is necessary than when the beat frequency is the result of the diflerence betwcentwo high frequencies. A further object of my invention is to provide means for efiiciently producing signals of the desired character. Another object of my invention is to provide suitable receiving ap paratus for rendering audible at the receiving station the signals sent from the transmitting station and for enablin the receivin operator to readily between e ects produced by the static shocks and those produced by the desired signal. another object of my invention is to for limiting the amount provide a means -70 considerably beyond the time during which of of the static shocks whichean be tran ltted to the receiving apparatus without at the same time limitin the energy of the signal which will act pon the receiving apparatus.

The features of m invention which I believe to be patentab e are ointed out with articularity in the appen ed claims. The invention itself however, together with further objects and advantages thereof, will best be understood by{ reference to the following description ta en in connection with the accompanying drawing in which Figs. 1 and 2 illustrate diflerent modifications of the circuit connections which may be emploved in receiving signals in accordance with my invention.

In the circuit arrangement shown in Fig. 1, continuous wave signals are received upon the antenna 1 which may be aperiodic or strongly damped, so that it will not be set into oscillation by static shocks. A high frequency source of current 2 is also coupled to the antenna 1 by means of a coupling transformer 3. The local source of current should be of a frequency differing from that of the received signals by an amount above audibility. The current having amplitude pulsations which results from the interaction between the current from the local source and the signaling current is impressed upon a circuit which includes the grid 4 of an amplifier 5 of the electron discharge type comprising a heated cathode 6 and cooperating anode 7 with a battery 8 in the external circuit between cathode and anode. A few of the cells 9 of this battery may also be connected between cathode and grid in order to adjust the grid potential to a value at which the device is most eflicient in amplifying the received signals. The current flowing in the circuit of this amplifier which comprises electrodes 6 and 7, and battery 8, which for convenience in description I designate the plate circuit, will be a pulsating current. The alternating current component of this current will flow in the secondary of transformer 10 and the circuit 11 which comprises the secondary of this transformer, inductance 12. and variable condenser 13 is tuned to the frequency of the amplitude pulsations of the current im ressed upon the amplifier 5. The impu ses act accumulatively until the current in circuit 11 has attained its maximum amplitude. If this circuit is a highly tuned circuit the time during which the current amplitude will be built up may be as much as that covered by 100 cycles of the amplitude pulsations; that is, if the frequency of these pulsations is 5000 cycles it may require 1/50of a second for the oscillating circuit n'to'" reach this maximum. If the radio frequency is 50,000 .cycles the. time for the oscillating circuit 11. to reach its maximum against the may correspond to 1000 cycles of the radio frequency and thus it is apparent that the energy stored in the oscillating circuit may represent the accumulated ener of 1000 cycles of the radio frequency. e antenna as well asthe secondary oscillating circuit will also be affected by static shocks and to a certain degree accumulatively. However, it can be proven by the law of probability that the accumulative effect of successive static shocks in any oscillating circuit increases by the square root of the time in which these irregular shocks are taking place, whereas the oscillations due to the signal, if this is a continuous wave, increases arithmetically until the circuit has ap proached its maximum amplitude. While it can therefore not be expected that the secondary oscillating circuit will be free from static disturbances the relative intensity of the signal and the static is greater the longer the time during which the energy of the signal can accumulate. In order to make the signal audible a local source of alternating current 14 of slightly different frequency from that of the current in circuit 11 is introduced in the grid circuit of amplifier 15, so as to create beats in the receiver 16 which is inserted in the plate circuit of this amplifier and detect the current of secondary frequency by the well known heterodyne method. In previous attempts which have been made to suppress static by tuning for an audible group frequency in a spark system or its equivalent, the operator has been required to distinguish between the signal and static by the pitch of the note which is heard in the receiving telephone. In this case although tuning is applied to the circuit of the audible group frequency and the intensity of the currents produced by static relative to the intensity of the signal has been decreased in somewhat the same manner as that described, there has been pactically no gain by reason of this action cause of the fact that the currents produced by static are changed to a pitch for which the ear is particularly sensitive, and in fact, are changed to a pitch similar to the signal. In my system, however, in which the secondary tuning is at an inaudible frequency the receiving device discriminates between currents of the static and the signal purely by magnitude and the tone pitch at which the signal is received is regulated independently by the heterodyne receiver without reference tothe frequency of the discriminating oscillatory circuit In the arran ement shown in Fig. 2, I have illustrate an additional safeguard transmission of static shocks to the receiving circuit in which an iron core transformer is substituted for the transformer 10 of Fig. 1. This transformer is normal strength of a iron at its maximum permeabilit whereas an sudden and excessive shoc sby static wi l saturate the iron so that full force of the shock will not be transmitted to the secondary This transformer is, in other words, a volta limiting transformer which is capable o transmittin without saturation a. volta only slig tly in excess of that produce by the signals. As indicated in the drawing the transformer in the present case comprises two cores 17 and 18, each having a rlmary winding 19 and a secondary win in 20. In order to regulate the saturation o transformer a third winding 21 which is common to the two cores, is supplied with a direct current from battery 22, and the value of the current thus su plied may be adjusted in order to secure the desired degree of saturation.

While I have shown and described only two different receiving systems whereby my invention may be carried into effect, it is a parent that many modifications may o made in the circuit arrangements as well as in the particular form of apparatus used without departing from the scope of my invention as set forth in the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States, is,

1. The method of receiving continuous wave signals which consists in combining the received current with the current from a local source differing therefrom in freguency so that beats are produced having a requency above audibility, amplifying and recti ing the current thus produced, passing t e rectified current through a circuit which is resonant to the freiquency of the beats, and then rectifying the alternating current flowing in this resonant circuit.

2. The method of receiving wireless si nals which consists in combining the signifiing current with a local source of high frequency current so as to produce a current of radio frequency with amplitude pulsations of much lower frequency but above audibility, producing from this current having amplitude pulsations an alternating current having a frequency corresponding to the frequency of the amplitude pulsations, accumulating the energy of this alternating current in a resonant circuit and utilizing the accumulated energy for the operation of suitable detectin a paratus.

3. The method of receiving wireless signals which consists in combining the signaling current with a current having a frequency differing therefrom by an amount above audibility, producing from these currents an alternating current with a frequency corresponding to the difference between the frequencies of the two currents, accumulating the energy of the last named so designed that the signal will work the this lurality of alternating current during a y detecting successive c cles and selective the energy t us accumulated.

4. The method of receiving wireless signals which consists in producing at the receiving station a radio frequency current having definite amplitude pplsations of a frequency above audibility y causing the signalin current to interact with a local source 0 high frequency current, producing an alternating current of a frequency corres ondin to the said amplitude pulsations, an selectively receiving and detecting the alternating current thus produced.

5. The combination in a wireless signaling system, of an antenna for receiving continuous wave signaling currents, a local source of current of radio frequency differin in frequency from the signaling current y an amount above audibility, means for combining the signaling current with current from the local source to produce an alternatin current having a. fre uency above awfibility, a resonant circuit or accumulating the energy of-the current thus produced, and means for detecting the energy thus accumulated.

6. The combination in a wireless signaling system, of an antenna for receiving continuous wave signaling current, a local source of current of radio frequency, means for combining the signaling current with current from the local source to produce a current of radio frequency having amplitude pulsations of much lower frequency, but above audibility, means for producin from this current an alternating current aving a frequency corresponding to the frequency of the amplitude pulsations, a resonant circuit for accumulatmg the energy of this alternating current, and detecting apparatus adapted to p be operated by the energy thus accumulated.

7. The combination in a wireless signaling system, of means at a receiving station for combining a continuous wave signaling current with a current from a local source having a frequency differing therefrom by an amount above audibility, means for roducing from the combined currents an a ternatin current having a frequency correspon mg to the difference between the frequencies of the two currents, a resonant circuit for accumulating the energy of this alternating current during a plurality of successive c cles,and meansfor detecting the ener t us accumulated.

8. e combination in a wireless signaling system, of means at a receiving station for combinin a signaling current with current from a ocal source of radio frequency to produce a radio frequency current having definite amplitude pulsations of a frequency above audibility,means for producing 111 said current having amplitude sations, an alternating current having a nals which consists in combining the signa quency correspon to the am litude p isations, and means r selective y receiving and detecting the alternating current thus produced.

9. The method of overcoming the effects of static disturbances in a wireless signaling stem, which consists in rece1v1ng the sign by means of a substantially aperiodic antenna, producing at the receivm station by means of the received si als an a local source a current of radio Eiiquency having amplitude pulsations of much lower freuency, amplifying the current thus prouced and producing thereby an alternating current havin a frequency corresponding to the amplitu e pulsations, and passing this current throu h a circuit containing a device for limiting the energy passing therethrough to a predetermined value, and then through a circuit which is resonant to the frequency of the alternating current.

10. The combination in a wireless receiving system, of a substantially aperiodic antenna, means for amplifying the signaling current received thereby, and an iron core transforming device in the circuit of the amplified current so adjusted that voltages appreciably exceeding those roduced by the signal will.v not be transmitte thereby.

11. The combination in a wireless receiving system, of an antenna, means for am lifymg the signaling current received there y, and an iron core transforming device in the circuit of the amplified current so adjusted that voltages appreciably exceeding those produced by the signals will not be transmitted thereby.

12. The method of receiving continuous wave signals which consists in combining the received current with the current from a local source differing therefrom in frequency so that beats are produced having a frequency above audibility, rectifying the current thus produced, producing from this rectified current an alternatin current having a freguency equal to the at fnequenc passing t e last mentioned current througi i a circuit which is resonant to its frequency and amplifying and detecting the alternating current of beat frequency.

13. The method of receiving wireless siging current with a'local source of high fre quency current so as to produce a current of radio frequency with amplitude pulsations of much ower frequency but above audi bility, producing from this current having amplitude pulsations an alternating current having a frequency corresponding to the fre- 2111161103. of the amplitude pulsations passing e last mentioned current through a circuit which is resonant to its frequency, and amplifying and detecting the alternating current flowing in said circuit.

14. The method of receiving wireless sighaving definite amplitude nals which consists in producing at the receiving station a radio frequency current pplsations of y a frequency above audibility y causing the signaling current to interact with a local source of high frequency current, producing an alternatin current of a frequency corresponding to t c said amplitude pulsations applying the resultant current to the input circuit of an electron discharge device, and thereby amplifying and detecting the alternatin current thus produced.

15. The com ination in a wireless signaling system, of an antenna for receiving continuous wave signali currents, a local source of current of ra io frequency difiering in frequency from the si naling current by an amount above audibi ity, means for combining the signaling current with current from the local sohrce to produce an al ternating current having a frequency above audibility, a circuit through which said alternating current is passed and which is resonant to the fr uency thereof and means for amplifying an detecting the alternating current flowing in said circuit.

16. The combination in a signaling system of means at a receiving station for combining a continuous wave signaling current with a current from a local source having a frequency differing therefrom by an amount above audibility, means for producing from the combined currents an alternating current having a frequency corresponding to the difierence between the frequencies of the two currents, and an electron ,dischar device for amplifying and detecting the a ternating current produced thereby.

17. The combination .in a wireless signaling system, ofmeans at a receiving station for combinin a signaling current with current from a coal source of radio frequency to Iproduce a radio frequency current having de nite am litude pulsations of a frequency above audi ility, means for producing from said current having amplitude pulsations, an alternating current having a frequency corresponding to the amplitude ulsations, and an electron discharge device or amplifying and detecting the alternating current thus produced.

18. The method of amplifying and receiving high frequency electrical oscillatory energy which comprises combining the incoming energy wit locally generated high frequency continuous oscillations of a frequency difierin from said incoming ener by a third hig frequenc converting t e combined ener by suitaiile means to roduce said thir high frequency oscillations, applying the resultant current to the in ut circuit of an electron discharge. am li er and thereby amplifying, detecting an indicating the said third high frequency oscillations.

19. The method of amlplifyin and receiving high frequency e ectrica oscillatory energy which com rises, combining the incoming energy wit locally generated high frequency continuous electrical oscillations of a. frequency differing from said incoming energy by a third high frequency, rectim the combined energy to produce said ir high frequency oscillations, assing said third high frequency osci lations through a circult which is resonant to this frequency and am 1i ing, detecting and indicating the said t ir high frequency oscillations.

20. The method of amplifying and receiving undamped wave high frequency electrical oscillatory energy which comprises combining the incoming energy with locally generated high frequenc continuous electrical oscillations o a fiequency differing from said incomin energy by a third readily-amplifiable hig frequency, amplifying the said third high frequency oscillations, combining said third high frequency electrical oscillations with locally nerated high frequency oscillations at a requency near to said third high frequency, converting the said last combined energ to roduce low fre uency oscillations an in icating the resu ting low frequency oscillations.

21. The method of indirectly amplifying high frequency electrical oscillatory ener which comprises combining said energy wfili high frequency continuous electrical oscillations of a frcquenc difi'ering from said energy by a third rea ilyamplifiable high frequency, converting the combined energy by suitable means to produce said readilyamplifiable high frequency oscillations and amplifying said resulting readily-amplifiable high frequency oscillations.

In witness whereof, I have hereunto set my hand this 13th day of July, 1918.

ERNST F. W. ALEXANDERSON.

'DISOLAIMER 1,508,151.--E'mat F. W. Alcmanderson, Schenectady, N. Y. Wmmms Smzunmo SYSTEM. Patent dated September 9, 1924 Disclaimer filed November 16, 1931,

by the assignee, Radio Oorporafian of America.

Hereby enters this disclaimer to claim 21 in the said specification which is in the following words, to wit:

The method of indirectly am lifying high frequency electrical oscillatory energy which comprises combining said energy with high frequency continuous electrical oscillations of a frequency differing from said energy by a third readily-amplifiable high frequenc converting the combined energy by suitable means to produce said readily-ampli able high frequency oscillations and amplifying said resulting readilyam lifiable high freguency oscillations.

Oficial Gazette member 8, 1.931.] 

